Immunosequestration: A new technique for studying peripheral iodothyronine metabolism in vitro

Marietta Borges, Zemach Eisenstein, Albert G. Burger, Sidney H. Ingbar*

*Corresponding author for this work

Research output: Contribution to journalArticlepeer-review


Studies of the pathways of peripheral metabolism of iodothyronines in vitro are often obscured quantitatively and qualitatively, both by the rapid degradation of products of interest and by the generation of a single product from more than one precursor. To overcome these problems, we tested the ability of rabbit immunoglobulin G containing antibodies against particular iodothyronines to inhibit the enzymatic degradation of their respective antigens. Such inhibition was indeed demonstrable in the case of all the iodothyronines tested, i.e. T3, rT3, and 3, 3'-diiodothyronine. The general method was then applied to studies of the ontogeny of peripheral iodothyronine metabolism in homogenates of chick embryo liver. By appropriate selection of antibodies and 125I-labeled substrates, it was shown that livers from immature embryos (<19–20 days of age) deiodinate T4 rapidly and almost entirely to rT3, with very little T3 being formed. In livers from embryos that had matured spontaneously or had been injected with hydrocortisone, T4 was deiodinated more slowly, but almost exclusively to T3. The findings indicate that the maturation of hepatic T4 metabolism involves an increase in the rate of 5′-monodeiodination coupled with a proportionately greater decrease in 5-monodeiodination, so that formation of T3 from T4 is increased and formation of rT3 is greatly retarded. The new technique, which we have termed immunosequestration, thus provided proof of conclusions reached only by inference in earlier studies that employed the in vitro techniques used in the past. The technique should prove valuable in studies of other problems related to peripheral iodothyronine metabolism and in other metabolic studies as well.

Original languageEnglish
Pages (from-to)1665-1671
Number of pages7
Issue number5
StatePublished - May 1981
Externally publishedYes


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